Light Detectives. Limb of Sun Very low mass star Brown dwarf Jupiter Light Detectives – #2

Light Detectives

Light DetectivesUsing NASA’s WISE Data to Identify Brown Dwarfs and ULIRGs

Limb of Sun

Very low mass star

Brown dwarf Brown dwarf

Jupiter

Brown dwarfs

Light Detectives – #2

Where is the brown dwarf?

Light Detectives – #3

How do astronomersknow what they know?

Light Detectives – #4

W1 = 3.4 microns

W2 = 4.6 microns

W3 = 12 microns2

COLOR

Regular Stars Brown Dwarfs(more green [W2], less blue [W1])

Light Detectives – #5

Where is the brown dwarf?

Light Detectives – #6

Light Detectives – #7

Let’s find a brown dwarf more scientifically using real NASA data

The Process:1. Find and download the data2. Make measurements3. Plot and interpret the

results

Finder Chart

• A finder chart shows you where to find objects in the sky.

• The same objects will appear in each of the WISE images you download.

Light Detectives – #8

How do astronomersknow what they know?

Light Detectives – #9

W1 = 3.4 microns

W2 = 4.6 microns

W3 = 12 microns2

COLOR

Regular Stars Brown Dwarfs(more green [W2], less blue [W1])

Light Detectives – #10

0.05 0.1 0.15 0.2 0.25 0.3 0.350.2

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54

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Sample color-color diagram for brown dwarf search W2/W1 vs W3/W2

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W3/W2

W2/

W1

• Brown dwarfs have LOW intensity in W1.

• Brown dwarfs are relatively BRIGHT in W2 light.

• What objects have high W2/W1 ratios?

• What objects have higher W3/W2 ratios than brown dwarfs?

Color-Color Diagram

Light Detectives – #11

0 1 2 3 4 5 6 7 8 9

W3/W2

W2/

W1

5 4

3 2 1

0

Brown Dwarfs

AGB Stars

Stars Normal Galaxies

ULIRGs

ULIRGsUltra-Luminous Infrared Galaxies

Light Detectives – #12

Light Detectives – #13

Arp 220

Light Detectives – #14

Finder Chart

• A finder chart shows you where to find objects in the sky.

• The same objects will appear in each of the WISE images you download.

Light Detectives – #15

0.0 1.0 2.0 3.0 4.0 5.0 6.00.0

0.2

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1.0

1.2

12

11

1098

765

432

1

Sample color-color diagram for ULIRG searchW2/W1 vs W3/W2

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W3/W2

W2/

W1

Light Detectives – #16

WISE color image

Light Detectives – #17

WISE color imageHubbleimage

ULIRG created by two merging galaxies!